On 2021-01-23 12:20, Andrei POPESCU wrote:
On Vi, 22 ian 21, 22:26:46, mick crane wrote:
hello,
I want to tidy things up as suggested.
Have one old PC that I'll put 2 disks in and tidy everything up so
what's
scattered about is on the running disks and this new/old one is just
backup
for them.
Can I assume that Debian installer in some expert mode will sort out the
raid or do I need to install to one disk and then mirror it manually
before
invoking the raid thing ?
The "raid thing" is a separate layer below the partitions and file
systems.
Technically it is possible to create the mirror with just one device (I
believe mdadm calls this "degraded"), partition the md mirror device,
install, copy data to it, etc., add the second device later and let md
synchronize the two drives.
Because Linux RAID is a separate layer with no knowledge of the data
"above" it has to copy every single bit to the other drive as well
(similar to a dd device-to-device copy), regardless if actually needed
or not.
If you are really strapped for space and must do this ZFS can do it much
more efficiently, because it controls the entire "stack" and knows
exactly which blocks to copy (besides many other advantages over Linux
RAID).
Unfortunately ZFS is slightly more complicated from the packaging side,
and installing Debian on a ZFS root is difficult.
It still makes an excelent choice to manage your storage drives,
especially on a stable system, where there is less hassle with the dkms
module and it's amazingly simple to use once you familiarise yourself
with the basics.
Kind regards,
Andrei
Sigh, OK I take advice and have a go.
Really I just want to get on and do some drawings or something but I
think I'll thank myself later if I get proper backup in place.
If after having a quick look am I understanding anything?
Partition and install minimal Debian with no X or anything on just one
disk.
install headers and zfs-utils.
Add other disk and then what ? To make it a mirror pool (like raid1)
does zfs take care of the partitions.
Do I want to delete all partitions on other disk first or make like for
like partitions?
If that's done and I've made a zpool called "backup" from then on the
ZFS is nothing to do with the kernel ?
I ask kernel make a directory "my_pc1"
then
"zfs create -o mountpoint=/my_pc1 backup/my_pc1"
I ask kernel make a directory "my_pc2"
then
"zfs create -o mountpoint=/my_pc2 backup/my_pc2"
So then I can copy files from other PC (pc1) to
"my_backup_pc/backup/my_pc1" and ZFS mirrors the data to other disk in
pool ?
If that's how it works I'll just need something on the backup_pc and the
other PCs to automate the backing up.
Is that backup Ninja or something ?